The present invention relates to a camera equipped with a lens barrel having a camera lens and a finder which varies magnification based on a movement of the lens barrel in the optical axis direction, and to an adjusting method for the field ratio of a zoom finder of the camera.
In the field of a zoom camera, there has recently been available a zoom camera wherein plural zoom areas are provided, and a zoom button is operated to stop a zoom lens stepwise in the plural zoom areas to change a focal length of the zoom lens. By stopping stepwise in this manner, a zoom mechanism is simpler than that in a zoom camera wherein a lens barrel can be stopped continuously on a stepless basis, thus, a small-sized and inexpensive zoom camera can be achieved.
In general, in the zoom camera wherein a lens is stopped stepwise, when a zoom button is operated, a lens barrel having a camera lens stops at a waiting position corresponding to a prescribed zoom area in accordance with the operation of the zoom button, then, by conducting release operation for photographing, the lens barrel is protruded to the focal point position determined by a subject distance, so that photographing may be conducted.
On the other hand, a finder is a zoom finder whose magnification is varied based on a change of a focal length of the zoom lens, namely on a movement of the lens barrel, and when the lens barrel stops at the prescribed waiting position, the photographing area can be confirmed with a field ratio corresponding to the zoom area.
As stated above, even in the case of a zoom camera which stops stepwise, when a lens barrel stops at the waiting position of the prescribed zoom area, a finder needs to have an appropriate field ratio corresponding to the zoom area. However, even when a finder is set to the waiting position calculated for obtaining the prescribed field ratio of the finder in each zoom area, errors are caused by dispersion of parts and by dispersion of assembly, thus, improvement of accuracy of parts and improvement of assembly accuracy are required for obtaining an appropriated field ratio.
This equally applies to the mechanism wherein a lens barrel and a finder are mechanically joined, and the finder moves when the lens barrel is moved by one driving source, and to the mechanism wherein a movement of a lens barrel is detected, and a finder is driven by a driving source other than the lens barrel and by a driving mechanism, for example. The necessity for improvement of accuracy of parts and for improvement of assembly accuracy stated above has resulted in a cause of cost increase of a camera. Therefore, the novel structure of a zoom camera including a field ratio adjusting method for a zoom finder has been desired.
The invention has been achieved to solve the problems mentioned above. Namely, the first object is to provide a camera equipped with a finder which less affects the camera in terms of cost and has an appropriate field ratio in accordance with a change in a focal length of a zoom lens, and to provide a zoom finder field ratio adjusting method. Further, the second object is to provide a camera equipped with a finder which less affects, in terms of cost, a zoom camera wherein a lens stops stepwise at plural zoom areas and has an appropriate field ratio in accordance with a change in a focal length of a zoom lens, and to provide its zoom finder field ratio adjusting method.
The objects of the invention are attained by taking the following structures.
The objects stated above are attained by either one of the following structures.
Structure (1) A camera comprising lens barrel having a lens; a driving means which drives the lens barrel so that it moves in a direction of an optical axis of the lens; a finder of which magnification varies in accordance with a movement of the lens barrel driven by the driving means; a position sensor which detects the position of the lens barrel; a controller which controls the driving means so that the lens barrel driven by the driving means moves in the direction of the optical axis and stops at plural positions in the direction of the optical axis; and a memory which stores plural position data relating to the plural positions stated above, wherein the controller controls the driving means so that the lens barrel is capable of stopping at plural positions in the direction of the optical axis for magnification variation of the lens, based on results of detection by the position sensor and at least one of the plurality of position data stored in the memory.
Structure (2) The camera according to Structure (1), wherein the memory stores at least one of the position data for each of the plural positions.
Structure (3) The camera according to Structure (1), wherein the memory stores at least one of the position data being different from others.
Structure (4) The camera according to Structure (1), wherein the controller controls the driving means so that the lens barrel may stop stepwise at plural positions in the direction of the optical axis for the magnification variation of the lens.
Structure (5) The camera according to Structure (2), wherein the position sensor has an absolute position sensor which detects an absolute position of the lens barrel and a relative position sensor which detects a relative position of the lens barrel from the absolute position, and the controller controls the driving means in accordance with the results of detection by the absolute position sensor, the results of detection by the relative position sensor, and with the position data.
Structure (6) The camera according to Structure (2), wherein the controller selects the position data corresponding to the position of the lens from position data stored in the memory, and controls the driving means based on the selected position data.
Structure (7) The camera according to Structure (5), wherein the relative position sensor has a first relative position sensor and a second relative position sensor which detects relative positions of the lens barrel with the resolving power that is higher than that of the first relative position sensor.
Structure (8) The camera according to Structure (2), wherein the memory is EEPROM.
Structure (9) A camera finder field ratio adjusting method comprising a step to move a lens barrel having a lens in a direction of an optical axis, and to store in a memory the first information related to the first position representing the position of the lens barrel where the field ratio of a finder which varies in accordance with a movement of the lens barrel is a prescribed value, and a step to move the lens barrel in the direction of the optical axis, and to store in the memory the second information related to the second position representing the position of the lens barrel where the field ratio of the finder is a prescribed value, the second position is different from the first position, wherein the first position and the second position are those where the lens barrel stops after the magnification variation.
Structure (10) A finder field ratio adjusting method for a camera having a lens barrel which has a lens and moves in the direction of the optical axis to stop at plural zoom areas in the direction of the optical axis and having a finder which varies magnification in accordance with a movement of the lens barrel,
wherein there are provided a step to move the lens barrel in the direction of the optical axis and thereby to store the first information related to the first position representing the position of the lens barrel where the field ratio of the finder is a prescribed value in the first area among plural zoom areas, and a step to move the lens barrel in the direction of the optical axis and thereby to store the second information related to the second position representing the position of the lens barrel where the field ratio of the finder is a prescribed value in the second area among plural zoom areas.
Structure (11) The method according to Structure (10), wherein the first position is a stop position for the lens barrel after magnification variation in the first area, and the second position is a stop position for the lens barrel after magnification variation in the second area.
Preferable structures are as follows.
Structure (12) A zoom camera having a lens barrel which has a zoom lens and stops stepwise at plural zoom areas and having a finder which varies magnification based on a movement of the lens barrel in the optical axis direction, comprising an operating means to operate the lens barrel, a driving means to drive the lens barrel, a position detecting means which detects position of the lens barrel, a control means which drives the lens barrel with the driving means in accordance with operations of the operating means and controls driving of the lens barrel so that the lens barrel may stop at each waiting position corresponding to each of the plural zoom areas, referring to the results of detection by the position detecting means, and a memory means which makes a waiting position of the lens barrel for at least one zoom area to be variable, and stores position data of the waiting position corresponding to the prescribed finder field ratio, wherein the control means controls the lens barrel to be at the waiting position based on position data stored in the memory means.
Structure (13) The zoom camera according to Structure (12), wherein the position detecting means has an absolute position detecting means which detects an absolute position of the lens barrel and a relative position detecting means which detects a relative position from the absolute position.
Structure (14) The zoom camera according to Structure (13), wherein the relative position detecting means has the first relative position detecting means and the second relative position detecting means which detects the relative position of the lens barrel under the resolving power which is higher than that in the first relative position detecting means.
Structure (15) The zoom camera according to either one of Structures (12)-(14), wherein all waiting positions of the plural zoom areas are variable, and the memory means stores position data of each waiting position corresponding to a prescribed field ratio for each of the plural zoom areas.
Structure (16) The zoom camera according to either one of Structures (12)-(15), wherein the memory means is EEPROM.
Structure (17) A zoom finder field ratio adjusting method for a zoom camera having therein a lens barrel which has a zoom lens and stops stepwise at plural zoom areas, an operating means to operate the lens barrel, a driving means to drive the lens barrel in the optical axis direction, a position detecting means to detect the position of the lens barrel in the optical axis direction, and a finder which varies magnification based on a movement of the lens barrel in the optical axis direction, wherein there is provided a control means which makes the driving means to drive a lens barrel in accordance with operations of the operating means, and controls the lens barrel so that it may stop at each waiting position corresponding to each of the plural zoom areas while referring to the results of detection by the position detecting means, while, a waiting position for the lens barrel for at least one zoom area is variable, and position data of the waiting position corresponding to the prescribed finder field ratio are stored in the memory means, and the control means controls the lens barrel to be at the waiting position corresponding position data stored in the memory means.